Longitudinal Spin Seebeck Effect Thermopiles Based on Flexible Co-Rich Amorphous Ribbons/Pt Thin-Film Heterostructures.

Thermoelectric phenomena, such as the Anomalous Nernst and Longitudinal Spin Seebeck Effects, are promising for sensor applications in the area of renewable energy. In the case of flexible electronic materials, the request is even larger because they can be integrated into devices having complex shape surfaces. Here, we reveal that Pt promotes an enhancement of the thermoelectric response in Co-rich ribbon/Pt heterostructures due to the spin-to-charge conversion.

Anomalous Nernst Effect in Flexible Co-Based Amorphous Ribbons.

Fe3Co67Cr3Si15B12 ribbons with a high degree of flexibility and excellent corrosion stability were produced by rapid quenching technique. Their structural, magnetic, and thermomagnetic (Anomalous Nernst Effect) properties were studied both in an as-quenched (NR) state and after stress annealing during 1 h at the temperature of 350 °C and a specific load of 230 MPa (AR). X-ray diffraction was used to verify the structural characteristics of our ribbons.

High Performance of Metallic Thin Films for Resistance Temperature Devices with Antimicrobial Properties.

Titanium-copper alloy films with stoichiometry given by Ti1-xCux were produced by magnetron co-sputtering technique and analyzed in order to explore the suitability of the films to be applied as resistive temperature sensors with antimicrobial properties. For that, the copper (Cu) amount in the films was varied by applying different DC currents to the source during the deposition in order to change the Cu concentration. As a result, the samples showed excellent thermoresistivity linearity and stability for temperatures in the range between room temperature to 110 °C.

Force Correlations in Disordered Magnets.

We present a proof of principle for the validity of the functional renormalization group, by measuring the force correlations in Barkhausen-noise experiments. Our samples are soft ferromagnets in two distinct universality classes, differing in the range of spin interactions, and the effects of eddy currents. We show that the force correlations have a universal form predicted by the functional renormalization group, distinct for short-range and long-range elasticity, and mostly independent of eddy currents.

Directional Field-Dependence of Magnetoimpedance Effect on Integrated YIG/Pt-Stripline System.

We investigated the magnetization dynamics through the magnetoimpedance effect in an integrated YIG/Pt-stripline system in the frequency range of 0.5 up to 2.0 GHz.

Improving the Room-Temperature Ferromagnetism in ZnO and Low-Doped ZnO:Ag Films Using GLAD Sputtering.

ZnO and doped ZnO films with non-ferromagnetic metal have been widely used as biosensor elements. In these studies, the electrochemical measurements are explored, though the electrical impedance of the system. In this sense, the ferromagnetic properties of the material can be used for multifunctionalization of the sensor element using external magnetic fields during the measurements.

Magnetic Response Dependence of ZnO Based Thin Films on Ag Doping and Processing Architecture.

Multifunctional and multiresponsive thin films are playing an increasing role in modern technology. This work reports a study on the magnetic properties of ZnO and Ag-doped ZnO semiconducting films prepared with a zigzag-like columnar architecture and their correlation with the processing conditions. The films were grown through Glancing Angle Deposition (GLAD) co-sputtering technique to improve the induced ferromagnetism at room temperature.

Waiting-time statistics in magnetic systems.

Many complex systems, from earthquakes and financial markets to Barkhausen effect in ferromagnetic materials, respond with a noise consisting of discrete avalanche-like events with broad range of sizes and durations, separated by waiting times. Here we focus on the waiting-time statistics in magnetic systems. By investigating the Barkhausen noise in amorphous and polycrystalline ferromagnetic films having different thicknesses, we uncover the form of the waiting-time distribution in time series recorded from the irregular and irreversible motion of magnetic domain walls.

A new heterofunctional support for enzyme immobilization: PEI functionalized FeO MNPs activated with divinyl sulfone. Application in the immobilization of lipase from Thermomyces lanuginosus.

Lipase from Thermomyces lanuginosus (TLL) was immobilized onto a novel heterofunctional support, divinyl sulfone (DVS) superparamagnetic nanoparticles (SPMNs) functionalized with polyethyleneimine (PEI). Particle size and zeta potential measurements, elemental analysis, X-ray powder diffraction, magnetic measurements, and infrared spectroscopy analysis were used to characterize the TLL preparations. At pH 10, it was possible to achieve 100 % of immobilization yield in 1 h.

Modulating the Spin Seebeck Effect in CoFeAl Heusler Alloy for Sensor Applications.

The thermoelectric conversion technique has been explored in a broad range of heat-flow sensors. In this context, the Spin Seebeck Effect emerges as an attractive candidate for biosensor applications, not only for the sensibility improvement but also for the power-saving electronic devices development. Here, we investigate the Longitudinal Spin Seebeck Effect in films with a Co 2 FeAl/W bilayer structure grown onto GaAs (100) substrate, systems having induced uniaxial magnetic anisotropy combined with cubic magnetic anisotropy.

Anomalous Nernst effect in stressed magnetostrictive film grown onto flexible substrate.

The anomalous Nernst effect in nanostructured magnetic materials is a key phenomenon to optimally control and employ the internal energy dissipated in electronic devices, being dependent on, for instance, the magnetic anisotropy of the active element. Thereby, here, we report a theoretical and experimental investigation of the magnetic properties and anomalous Nernst effect in a flexible magnetostrictive film with induced uniaxial magnetic anisotropy and under external stress. Specifically, we calculate the magnetization behavior and the thermoelectric voltage response from a theoretical approach for a planar geometry, with magnetic free energy density that takes into account the induced uniaxial and magnetoelastic anisotropy contributions.

Further stabilization of lipase from Pseudomonas fluorescens immobilized on octyl coated nanoparticles via chemical modification with bifunctional agents.

The lipase from Pseudomonas fluorescens (PFL) was adsorbed on superparamagnetic NiZnFeO octyl-nanoparticles via interfacial activation, producing the biocatalyst OCTYL-NANO-PFL. In order to further improve the stability of the immobilized lipase, the immobilized enzyme biocatalyst was chemically modified with different concentrations of diverse bifunctional molecules (glutaraldehyde (GA), divinylsulfone (DVS) or p-benzoquinone (BQ)). The concentrations of bifunctional agents were varied (0.

Playing with universality classes of Barkhausen avalanches.

Many systems crackle, from earthquakes and financial markets to Barkhausen effect in ferromagnetic materials. Despite the diversity in essence, the noise emitted in these dynamical systems consists of avalanche-like events with broad range of sizes and durations, characterized by power-law avalanche distributions and typical average avalanche shape that are fingerprints describing the universality class of the underlying avalanche dynamics. Here we focus on the crackling noise in ferromagnets and scrutinize the traditional statistics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films having different thicknesses.

Universal properties of magnetization dynamics in polycrystalline ferromagnetic films.

We investigate the scaling behavior in the statistical properties of Barkhausen noise in ferromagnetic films. We apply the statistical treatment usually employed for bulk materials in experimental Barkhausen noise time series measured with the traditional inductive technique in polycrystalline ferromagnetic films having different thickness from 100 to 1000 nm and determine the scaling exponents. Based on this procedure, we group the samples in a single universality class, since the scaling behavior of Barkhausen avalanches is characterized by exponents τ∼1.